Seal assembly

ABSTRACT

A seal assembly comprising a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure and the movable stator for biasing the movable stator to a non-sealing position.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/830,236 filed Jul. 30, 2007.

FIELD OF THE INVENTION

The invention generally relates to gas turbine engines and morespecifically to seal assemblies used with gas turbine engines.

BACKGROUND OF THE INVENTION

Gas turbine engines displace large volumes of pressurized fluid, such asair through the engine fluid flowpath, during operation. Seal assembliesprevent the fluid from leaking undesirably by restricting fluid flowfrom areas of higher pressure to areas of lower pressure. The sealassemblies may be positioned between engine stationary and rotatingmembers. The seals compensate for transient variations in the gapsbetween adjacent engine component parts.

Because of the working environment of the seal assemblies, and/or theoperating environment, at least some known seal assemblies maydeteriorate over time. If the seals do not provide the required seal,fluid will leak past the seal detrimentally affecting the operation ofthe engine. Fluid leakage through gas turbine engine seal assemblies maysignificantly increase fuel consumption and adversely affect engineefficiency. Additionally, fluid leakage may cause damage to other enginecomponents and increase overall engine maintenance costs.

To facilitate sealing gaps defined between regions of high and lowpressure at least some known seal assemblies, such as the seal assemblydescribed in U.S. Pat. No. 5,284,347, for example, use aspirating air tocontrol leakage. The aspirating air prevents the rotating member fromcontacting the stationary member to facilitate accommodating transientvariations in the gap defined between the rotating and stationarymembers with little or no deterioration of the seal over the life of theseal assembly. However, because of the number of discrete componentscomprising such a seal assembly, such seal assemblies may be complex toinstall in the engine, and the weight of such assemblies will increaseengine weight which has a direct negative impact on engine performance.Moreover, because of the number of seal assembly components, theoperating efficiency of such seal assemblies may be contingent on thetolerances between the rotating and stationary members.

There is a need to develop a seal assembly that has relatively fewparts, effectively prevents leakage of fluid within a turbine engine anddoes not deteriorate over time.

BRIEF DESCRIPTION OF THE INVENTION

A seal assembly comprising a first movable stator member movable betweena sealing position and a non-sealing position, a second fixed statormember, the first stator member being movable relative to the secondstator member, the seal assembly further comprising at least one flexuremember coupled to the second stator member, and at least one biasingmember coupled between the at least one flexure and the movable statorfor biasing the movable stator to a non-sealing position.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the invention, it is believed that theembodiments set forth herein will be better understood from thefollowing description in conjunction with the accompanying figures, inwhich like reference numerals identify like elements, and in which:

FIG. 1 is a schematic illustration of an exemplary gas turbine engine;

FIG. 2 is a cross-sectional view of an exemplary seal assembly that maybe used with the gas turbine engine shown in FIG. 1, with a movablesealing member in a first position;

FIG. 3 is a cross-sectional view of the exemplary seal assembly of FIG.2 with the movable sealing member in a second sealing position;

FIG. 4 is a cross-sectional view of an exemplary seal assembly that maybe used with the gas turbine engine shown in FIG. 1, with a movablesealing member in a first open position;

FIG. 5 is a cross-sectional view of the exemplary seal assembly of FIG.4 with the movable sealing member in a second sealing position;

FIG. 6 is a front view of a flexure member useful with the sealassembly;

FIG. 7 is an alternate embodiment flexure member useful with the sealassembly;

FIG. 8 is a side view of the exemplary seal of FIG. 2, in a firstposition;

FIG. 9 is an isometric view of the exemplary seal of FIG. 2, in thefirst position;

FIG. 10 is an isometric view of the seal of FIG. 2 in the second sealingposition, similar to the cross-sectional view shown in FIG. 3;

FIG. 11 is an isometric view of the second stator member (102 of FIG.2);

FIG. 12 is an illustration of a possible alternate flexure member;

FIG. 13 is a front partial view of another embodiment of a flexuremember, similar to that of FIG. 6, useful with the seal assembly;

FIGS. 14 and 15 are enlarged partial views of the flexure member of FIG.13;

FIG. 16 is a front partial view of another embodiment of a flexuremember, similar to that of FIG. 6, useful with the seal assembly;

FIGS. 17 and 18 are enlarged partial views of the flexure member of FIG.16;

FIG. 19 is a front partial view of another embodiment of a flexuremember, similar to that of FIG. 6, useful with the seal assembly; and

FIG. 20 is an enlarged partial view of the flexure member of FIG. 19.

DETAILED DESCRIPTION OF THE SPECIFICATION

Although the invention is herein described and illustrated inassociation with a compressor to turbine interface for a gas turbineengine, it should be understood that the present invention may be usedto facilitate controlling leakage of any fluid between any region ofgenerally high pressure and any region of lower pressure.

Herein, the present invention seal assembly provides a simplified sealwith a reduced part count relative to prior art seals therebysimplifying the seal assembly, and reducing the weight of the sealassembly. For example, spring assemblies used in related seal assemblieshave been replaced by one or more flexure members. As will be describedherein the flexure member is attached between a non-contact seal slideand a stator. Also, secondary seal assemblies of prior art sealingdevices have been replaced with a single piston ring seal. The singlering seal may be retained within either a fixed or sliding stators. Thedesign may incorporate one or more flexure members, the number thereofdepending upon the design requirement.

FIG. 1 is a schematic illustration of an exemplary gas turbine engine 10including a fan assembly 12 and a core engine 13 including a highpressure compressor 14, and a combustor 16. Engine 10 also includes ahigh pressure turbine 18, a low pressure turbine 20, and a booster 22.Fan assembly 12 includes an array of fan blades 24 extending radiallyoutward from a rotor disc 26. Engine 10 has an intake side 27 and anexhaust side 29. In one embodiment, the gas turbine engine is aGE90-115B that is available from General Electric Company, Cincinnati,Ohio. Fan assembly 12 and turbine 20 are coupled by a first rotor shaft31, and compressor 14 and turbine 18 are coupled by a second rotor shaft33.

During operation, air flows axially through fan assembly 12, in adirection that is substantially parallel to a central axis 34 extendingthrough engine 10, and compressed air is supplied to high pressurecompressor 14. The highly compressed air is delivered to combustor 16.Airflow (not shown in FIG. 1) from combustor 16 drives turbines 18 and20, and turbine 20 drives fan assembly 12 by way of shaft 31.

FIG. 2 is a cross-sectional view of an exemplary seal assembly 100 thatmay be used within gas turbine engine 10. In the exemplary embodiment,gas turbine engine 10 includes stationary stator member 102 coupled toframe 103 and a rotating member 104. In one embodiment, rotating member104 is a rotor that is rotatably coupled within engine 10 to rotateabout the axis of rotation 34. Frame 103 is a stationary circumferentialmember positioned around an axis of rotation 34 (not shown in FIG. 2).Frame member 103 includes an attachment flange 108 that extendsoutwardly away from the frame. In one embodiment, frame 103 may becomprised of the casing of gas turbine engine 10. As air flows throughengine 10, frame 103 is configured to help contain flowpath air.

Stationary stator member 102 of seal assembly 100 is a stationary memberthat extends circumferentially around the axis of rotation 34 of gasturbine engine 10. The stator is comprised of a base 112 and a flangemember 109. The base includes a base sealing surface 90 and a stopsurface 113. The flange and base are perpendicular. As shown in FIG. 2,stationary stator member 102 is fixed to frame 103 by fastener 107. Thefastener may be comprised of a conventional bolt member or othersuitable fastening means. The stator flange 109 and frame flange 108 arecoupled by the fastener member 107. A flexure member 150, which will bedisclosed in greater detail below is sandwiched between the head 190 offastener 107 and a surface 114 of flange 109 of fixed stator 102.

Seal assembly 100 also is comprised of moveable stator member 110includes a sealing face 124 and a plurality of sealing teeth 127, 128that extend outward from a portion of the sealing face 124. The stator110 is movable axially, in direction generally represented by directionarrow 200 in FIG. 2. In the exemplary embodiment, sealing face 124 issubstantially parallel to a rotating member surface 125 of rotatingmember 104. In a first position shown in FIG. 2, the sealing face 124 islocated at a distance 123 away from rotating member 104. The movablestator 110 of seal assembly 100 is located in the first position whenthe turbine engine is not in use with no fluid flowing through theengine flowpath.

Moveable stator member 110 also includes an opening 135 defined therein.The opening extends in the axial direction 200 when the movable statoris correctly coupled with flange 108. As shown in FIG. 2, the openingextends through the movable stator surfaces 124 and contact surface 118.When the movable stator is in the first, retracted position, surfaces118 and 113 are in contact. This contact between movable stator 110 andflange 108 controls the displacement of the stator 110 to the firstposition.

In the exemplary embodiment, openings 135 are oriented substantiallyperpendicular to rotating member surface 125. As described below in moredetail, openings 135 help to prevent contact between the movable member110, and specifically the plurality of teeth 127, 128; and rotatingmember 104. The movable stator may include any number of openings 135but for purposes of disclosing the exemplary embodiment, one or moreopenings 135 may be included in movable stator 110. Moveable statormember 110 further includes at least one radially extending opening 134.For purposes of disclosing the exemplary embodiment, a plurality ofopenings 134 are illustrated. However, any suitable number of radialopenings 134 may be provided in stator 110. The opening 134 extendsthrough surfaces 119 and 121 of the moveable stator member 110. In theexemplary embodiment, each opening 135 is located adjacent openings 134.

Moveable stator member 110 also includes yoke 130. The yoke extendsradially and defines an opening 131 that receives a seal member 132. Theseal member may be made from any suitable sealing material. As shown inFIGS. 2 and 3, when seated in opening 131, a portion of the seal memberextends beyond the free end 129 of the yoke. When the movable and fixedstators are coupled as shown in the figures, the end of the seal thatextends beyond free end 129 is in sealing contact with contact surface90 of the fixed stator 102. The seal member may be a piston ring seal,for example. Note that in an alternate embodiment, the seal may besupported by stator 102 and engage a sealing surface along the movablemember.

FIG. 3 shows the moveable stator member 110 in a second position, alsoreferred to herein as a sealing position. When air is supplied to thegas turbine flowpath, the pressure of the air causes the movable statorto be displaced in direction 200. As the stator member is displaced,seal 132 remains in contact with sealing surface 90. As the moveablestator moves toward member 104, the magnitude of distance 123 is reducedfrom its maximum value when the movable stator member is in the firstposition shown in FIG. 2. As shown in FIG. 3, when the movable statorreaches the end of travel and is in the second position, the sealingface 124 and the rotating member surface 125 are proximate each other.

Seal assembly 100 also comprises at least one flexure member 150. Theflexure member is substantially flat. As assembled, one end of flexuremember is located proximate the flange member 109. This end isidentified as 157 in FIGS. 2 and 3. Ends 157 and 152 are joined bybiasing member 151. Member 151 is extendible from its retracted lengthshown in FIG. 2 to an extended length as shown in the sealing positionof FIG. 3.

The flexure member 150 comprises a weak spring which flexes out of planeto allow axial translation of the moveable stator member 110 relative tothe stationary stator member 102. The connection of the flexure member150 to the moveable stator member 110 is shown in these figures forsimplicity as being bolted to the frame 103, but integral with themoveable stator 110. It could alternatively be a separate piece, butsuch a configuration may increase weight, complexity, and part count.

FIGS. 9 and 10 show in isometric view (comparable to the views of FIGS.3 and 4) the bending of the flexure member (150 series of numbers). Theflexure member is fixed to stationary stator 108 by bolt connection 107.The flexure member also includes a biasing portion 151 that is madeintegral with the movable stator member 110 at flange 152. The flexuremember 150 may be integral with moveable stator member 110 and therebycast with that member 110.

The flexure member 150 serves as a biasing mechanism for moving themoveable stator member 110. The member 150 biases the movable statormember toward the first position of FIG. 2. The flexure member 150returns the movable member to the first non-sealing position when theair flow through the engine is reduced to a minimum level or the engineis shut off. The flexure member 150 also controls the translation ofmovable member 110 to account for relative axial motion between therotor 104 and the stator 103 during engine operation. A flexure member150 may be pre-loaded against a stop (surface 113) such that in anun-pressurized state the sealing face 124 is held in an open position,e.g., when the turbine engine 10 has been disengaged into the offposition. This condition prevents slide contact of the moveable statormember 110 with the rotor 104 at low or no activation pressures, suchcontact, when unintended, operating to damage the seal assembly 100 andthus hinder its performance.

FIG. 6 provides an exemplary flexure member 150. Flexure member 150 maybe made from one or more of known metals in the art including steel,titanium, iron and nickel. As shown, the flexure member 150 includes acentral opening 183 that centers the moveable stator member 110 aboutthe engine axis 34, and seams 160 which are openings that extend throughthe thickness of the flexure member 150 and define beams of materialtherebetween. The seams 160 permit the flexure member 150 to flex ordisplace in the desired manner, out of the plane of the Figure. Suchmovement of the flexure member 150 biases a moveable stator member 110in the required direction for example to either open or close the sealassembly 100 as directed or required.

As shown in FIG. 6, the flexure member includes three seam segments 160,however any number of seams in may be provided. The beam count may bealtered to achieve desired deflection at seal face 124, as shown in FIG.4. In the present embodiment, each of the seams comprises two arcuatesegments 190, 191 that are joined by a non-arcuate segment 192. Thenon-arcuate portion is oriented radially. As shown in FIG. 6, for asingle seam, one of the arcuate segments of each adjacent seam in theclockwise and counterclockwise directions relative to the single seam,is located in parallel to the arcuate segments of the single seam, andare separated by a radial distance approximately equal to the length ofthe radial segment 192. The flexure member 150 may be configured to bean annular member as shown in FIG. 6 with central opening 183 thatreceives the moveable stator member 110. Additionally the flexure membermay have any suitable seam arrangement. Alternative designs for theseams are illustrated in FIGS. 7 and 12. The suitable seam arrangementmay include adjacent beams being connected together. This connection maybe at their proximate ends, such as the connecting segment 162 depictedin FIGS. 19 and 20. Connecting adjacent beams may provide variousadvantages, depending upon material and construction details as well asthe operating environment. One potential advantage would be to increasethe vibration frequency of the beams, such as to move their vibrationfrequency out of the range expected to be encountered in normal and/orforeseeable engine operating conditions.

The seams 160 are openings within each flexure member 150 that have beencut therein into a pattern determined beforehand as suitable to enablethe flexure member 150 to flex and therefore bias as required. Asuitable method for cutting the seams 160 into the flexure member 150 isby electro discharge machining which process is well known by persons ofskill in the art. It is noted herein, though, that the methodology forcutting the seams 160 into the flexure member 150 forms no part of theinvention herein. In another embodiment herein, a flexure member 150 maybe cast such that the seams 160 are a by-product of the casting process;i.e., cast such that the openings are part of the process. Additionally,stress relief holes 161 may be added at the ends of the cut-out portionsof the seams 160, for example, as shown in FIGS. 13-18.

FIG. 7 provides a cut-out of a portion of an alternate configuration ofthe flexure member 150 of FIG. 6. In particular, a portion of a seam 160is shown enlarged. Herein, each darkened line of the seam 160 representsan opening through the flexure member 150. FIG. 6 illustrates a possibleconfiguration of a flexure member 150 (spring). Taking a sheet ofmaterial and cutting the indicated slots in it allows a small force todisplace the center of the sheet (feature 152 of FIG. 2) out of planefrom the periphery of the sheet (feature 150 of FIG. 2). FIG. 7 shows analternative configuration of these cuts. An infinite number of possibleconfigurations are possible, of which the ones shown in FIGS. 6, 7, and12 are shown as examples.

FIGS. 4 and 5 show an alternate embodiment seal assembly 100 of thepresent invention. FIG. 4 shows the movable stator in a firstnon-sealing position and FIG. 5 shows the movable stator in a second,sealing position. The seal 100 includes flexure members 150 located atopposite ends of an elongate fastener 107. The flexure members areseparated by spacer 155 that is slidably located on the fastener 107. Inthis alternate configuration, flexure members 150 are positioned in aparallel orientation and are held apart by a spacer 155. Spacer 155 is auseful but not required device between the two flexure members 150.

The flexure members 150 always act to open the seal (moving the movablestator member 110 to the position shown in FIG. 4). Air pressures duringengine operation overcome the spring forces of the flexure members 150to move the moveable stator member 110 to the closed position (FIG. 5).

As shown in FIGS. 4 and 5, two flexible members 151 are coupled betweenends 150 and 152 as described in conjunction with the description ofseal assembly 100. Both members 151 extend when the movable stator isdisplaced in direction 200 to a sealing position. Additionally, seal 132is in sealing contact with surface 90 of fixed stator base 102.

During operation, cooling air and/or fluids flow through gas turbineengine 10. When engine 10 is in operation, high pressure air flowstoward the aft engine end 29. A portion of the highly compressed airdischarged from high pressure compressor 14 is directed towards sealassembly 100 for use as cooling fluid. Seal assembly 100 facilitatessubstantially controlling fluid flow from a region of higher pressure137 to a region of lower pressure 140 within gas turbine engine 10. Thepressure differential between higher pressure region 137 and lowerpressure region 140 initiates flow through seal assembly 100. Thepressures acting on the moveable stator member 110 are such that thepressure forces overcome the spring force of the flexure member 151, andthe moveable stator member 110 will translate from the first position(shown in FIGS. 2 and 4) to the second, sealing position (FIGS. 3 and5).

Additionally, during operation, a portion of the high pressure air flowsthrough openings 135. In the exemplary embodiment, opening 135 is aplurality of feed openings. Openings 135 form a high pressure film orair bearing between surfaces 124 and rotating member surface 125. Theair bearing prevents moveable stator member 110 from contacting rotatingmember 104.

After air flows through opening 135, the air exits to the region oflower pressure 140. Also, a portion of air may leak past seal teeth 126,127, 128. Air that leaks past seal teeth 126, 127, 128 and that portionof the air that has exited opening 135 and flows radially outward, flowsthrough radial openings 134 to the region of lower pressure 140.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A seal assembly comprising: a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure member and the movable stator for biasing the movable stator to a non-sealing position.
 2. The seal assembly of claim 1 having at least two flexure members and two biasing members, each biasing member coupled to a flexure member.
 3. The seal assembly as claimed in claim 1, the second stator comprising a base and a surface along the base, the first stator comprising a sealing member that sealingly engages the contact surface of said base.
 4. The seal assembly of claim 3 wherein the first stator comprises a yoke, said member being located in said yoke.
 5. The seal assembly as claimed in claim 1 wherein the flexure member is supported on a fastener member.
 6. The seal assembly of claim 1, wherein said flexure member includes at least one seam which permits said flexure member to flex out of plane.
 7. The seal assembly of claim 6, wherein said seam comprises an opening through said flexure member.
 8. The seal assembly of claim 7, wherein said flexure member includes a plurality of seams, said seams defining at least one beam therebetween, said beam being connected to another beam at their proximate ends.
 9. The seal assembly of claim 8, wherein said flexure member includes at least one stress relief hole at the end of a seam.
 10. A seal assembly comprising: a first movable stator member movable between a sealing position and a non-sealing position, a second fixed stator member, the first stator member being movable relative to the second stator member, the seal assembly further comprising at least one flexure member coupled to the second stator member, and at least one biasing member coupled between the at least one flexure member and the movable stator for biasing the movable stator to a non-sealing position, said flexure member including at least one seam which permits said flexure member to flex out of plane, said flexure member includes a plurality of seams, said seams comprising openings through said flexure member and defining at least one beam therebetween, said beam being connected to another beam at their proximate ends, and said flexure member including at least one stress relief hole at the end of a seam. 